Percnon gibbesi
(sally lightfoot crab)

P. gibbesi is the most invasive decapod crustacean to have entered the Mediterranean Sea. The vessel-transported crab was first recorded in 1999 from the Balearic Islands and Sicily, and has since spread to the Tyrrhenian and Ionian coasts of Italy, and eastwards to Turkey and Libya. Everywhere it has formed thriving high-density populations in an amazingly short space of time. Habitat overlap was noted with the native grapsid Pachygrapsus marmoratus and the pebble crab Eriphia verrucosa. Its distribution patterns may suggest a spatial resource partitioning and exclusion of native crab species.

P. gibbesi is found over a wide latitudinal and temperature range extending from California to Chile, Florida to Brazil, and Portugal to the Gulf of Guinea (Manning and Holthuis, 1981; d’Udekem d’Acoz, 1999). The proposed mechanisms for the introduction and spread of P. gibbesi in the Mediterranean are larval transport by surface currents (Pipitone et al., 2001), and shipping (Galil et al., 2002). There is little data to support the plausibility of coastal adjective transport, beyond the crab’s long larval life span (up to 6 weeks). P. gibbesi inhabits a narrow subtidal zone (commonly at depths of 1-2 m). The crab’s life history characteristics: crevicolous habits and preferred habitat position itas a likely candidate for successful primary and secondary ship-borne transport (Coutts et al., 2003). The occurrence of P. gibbesi in the Balearic Islands, the Sicilian archipelago, Sardinia, the Parthenopean Islands, the Amalfitan coast, the little frequented island of Antikythira, and lately along the touristic Kas peninsula and Antalya, possibly points to the role of recreational vessels as vectors. P. gibbesi is found in shallow rocky habitats where it finds safety under boulders and in narrow crevices (Pipitone et al., 2001; Russo and Villani, 2005). The “… high affinity of this species for boulders” (Deudero et al., 2005), favours colonization of harbour breakwaters. Enclosed marinas have been shown to increase the chances of transport of alien species that occur in the harbour basin (Floerl and Inglis, 2003), and only a few ovigerous females may be needed to establish a viable population and expand its range. Further invasions are therefore likely.

Genetics

P. gibbesi was included in Schubart et al's (2000) study on the use of the mitochondrial 16S rRNA gene for phylogenetic and populations studies of Crustacea.

Reproductive Biology

Female P. gibbesi reach sexual maturity at a carapace length of 15.0-16.0 mm, the smallest ovigerous female sampled was 16.1 mm. Ovigerous females occur between the end of May and September; most mature females collected from July to October carried eggs, whereas nearly all the mature females collected between November and March were not ovigerous. Brood size ranged from 254 eggs to nearly 32,000 eggs in largest egg mass, brood size is correlated with carapace size. Juveniles < 15 mm) were first observed at the end of September and throughout the winter until March (Sciberras and Schembri, 2008). Off West Africa ovigerous females have been collected in February, March, April and August (Manning and Holthuis, 1981). 

Nutrition

P. gibbesi was observed to overlap in the shallow rocky intertidal zone with the native grapsid, Pachygrapsus marmoratus, and to a lesser degree with the native xanthid, Eriphia verrucosa (Sciberras and Schembri, 2008).

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Europe: DAISIE - Delivering Alien Invasive Species Inventories for Europe, Web-based service, http://www.europe-aliens.org

06/07/09 Original text by:

Bella Galil, National Institute of Oceanography, Israel Oceanographic &, Limnological Research, Israel